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Ch. 12 DNA Technology and Genomics
Taylor - Campbell Biology: Concepts & Connections 10th Edition
Taylor, Simon, Dickey, Hogan10th EditionCampbell Biology: Concepts & ConnectionsISBN: 9780136538783Not the one you use?Change textbook
All textbooksTaylor, Simon, Dickey, Hogan 10th EditionCh. 12 DNA Technology and GenomicsProblem 3
Chapter 12, Problem 3

The DNA profiles used as evidence in a murder trial look something like supermarket bar codes. The pattern of bars in a DNA profile shows
a. The order of bases in a particular gene.
b. The presence of various-sized fragments of DNA.
c. The presence of dominant or recessive alleles for particular traits.
d. The order of genes along particular chromosomes.

Verified step by step guidance
1
Understand the context of DNA profiling: DNA profiles are created using a technique called gel electrophoresis, which separates DNA fragments based on their size. This is a key concept to keep in mind when analyzing the options.
Recall that DNA fragments are generated by cutting DNA with restriction enzymes. These enzymes recognize specific sequences in the DNA and cut at those sites, producing fragments of varying lengths.
In gel electrophoresis, these DNA fragments are loaded into a gel and subjected to an electric current. Smaller fragments move faster and farther through the gel, while larger fragments move more slowly. This creates a pattern of bands that is unique to an individual.
Analyze the options: The pattern of bars in a DNA profile does not directly show the order of bases in a gene (option a), the presence of dominant or recessive alleles (option c), or the order of genes along chromosomes (option d). Instead, it reflects the presence of DNA fragments of different sizes (option b).
Conclude that the correct answer is based on the principle that DNA profiles represent the presence of various-sized fragments of DNA, as determined by gel electrophoresis.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

DNA Profiling

DNA profiling is a forensic technique used to identify individuals based on their unique DNA characteristics. It involves analyzing specific regions of DNA that vary greatly among individuals, resulting in a pattern that can be visualized similarly to a barcode. This method is crucial in criminal investigations as it can link a suspect to a crime scene or exonerate innocent individuals.
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DNA Polymerases

Restriction Fragment Length Polymorphism (RFLP)

RFLP is a technique used in DNA profiling that involves cutting DNA into fragments with restriction enzymes. The resulting fragments vary in size due to differences in the DNA sequence among individuals. These size variations are then separated by gel electrophoresis, creating a distinct pattern that can be compared between samples, much like a barcode.
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1b) Use Ligation Enzymes

Alleles and Genetic Variation

Alleles are different versions of a gene that can exist at a specific locus on a chromosome. The combination of alleles an individual possesses contributes to their genetic makeup and can influence traits. In DNA profiling, the presence of various alleles can lead to differences in fragment sizes, which are critical for distinguishing between individuals in forensic analysis.
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Related Practice
Textbook Question

Imagine you have found a small quantity of DNA. Fill in the following diagram, which outlines a series of DNA technology experiments you could perform to study this DNA.

<IMAGE>

a.

b.

c.

d.

e.


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Textbook Question

Which of the following would be considered a transgenic organism?

a. A bacterium that has received genes via conjugation

b. A human given a corrected human blood-clotting gene

c. A fern grown in cell culture from a single fern root cell

d. A rat with rabbit hemoglobin genes

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Textbook Question

A paleontologist has recovered a tiny bit of organic material from the 400-year-old preserved skin of an extinct dodo. She would like to compare DNA from the sample with DNA from living birds. Which of the following would be most useful for increasing the amount of DNA available for testing?

a. Restriction fragment analysis

b. Polymerase chain reaction

c. Molecular probe analysis

d. Electrophoresis

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Textbook Question

How many genes are there in a human sperm cell?

a. 23

b. 46

c. About 21,000

d. about 3 billion

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Textbook Question

When a typical restriction enzyme cuts a DNA molecule, the cuts are uneven, giving the DNA fragments single-stranded ends. These ends are useful in recombinant DNA work because

a. They enable a cell to recognize fragments produced by the enzyme.

b. They serve as starting points for DNA replication.

c. The fragments will bond to other fragments with complementary ends.

d. They enable researchers to use the fragments as molecular probes.

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